docs: def set_user_data(self, subid, userdata, params=None):
          ''' /v1/server/set_user_data
          POST - account
          Sets the cloud-init user-data (base64) for this subscription.
          Note that user-data is not supported on every operating
          system, and is generally only provided on instance startup.
  
          Link: https://www.vultr.com/api/#server_set_user_data
          '''
          params = update_params(params, {
              'SUBID': subid,
              'userdata': userdata
          })
          return self.request('/v1/server/set_user_data', params, 'POST')